Setting autoFocus={false} causes unexpected broken functionality

[tonypee]

The demo has autoFocus={true}, but if you change it to 'false' everything breaks. This is fairly unintuitive, and costly if you dont realize that that was the cause (my case)

https://codesandbox.io/s/radio-group-demo-forked-s8c6s?file=/src/index.js

[tonypee]

It seems that the Radio elements dont focus themselves when they become selected by keyboard, as that incorrectly relies on the autoFocus flag - here's a PR:
#19